...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Synthetic Metals >Density functional theory calculations of the local spin densities of 3-substituted thiophenes and the oligomerization mechanism of 3-methylsulfanyl thiophene
【24h】

Density functional theory calculations of the local spin densities of 3-substituted thiophenes and the oligomerization mechanism of 3-methylsulfanyl thiophene

机译：3-取代噻吩局部自旋密度的密度泛函理论计算及3-甲基硫烷基噻吩的低聚机理

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

For obtaining a theoretical basis for the one-step formation of regioregular alpha-conjugated oligo- and polythiophenes, the electronic states of 3-substituted thiophenes and oligo(3-methylsulfanylthiophene)s were elucidated by molecular orbital calculations using density functional theory (DFT) with the Becke-type three parameters functionals (B3LYP) and the 6-31G(d) basis set. The reactivity for coupling reaction of mono- and oligo-thiophenes are inferred from the calculated unpaired electron spin densities of the respective radical cations, and the ionization potentials which correspond to the energies for generating radical cations during oxidative processes were estimated. The major regioselective products of the oligomerization of 3-(methylsulfanyl)thiophene (J. Org. Chem. 61(1996) 8285) can be well understood in terms of the magnitude of spin densities. Since the steric hindrance between the methylsulfanyl side chains does not interfere with the coupling reaction occurring between 2-positions (C-2) of thiophene rings, the initiating reaction of 3-(methylsulfanyl)thiophene is the generation of a head-to-head (HH) dimer. On the other hand, the head-to-tail (HT) dimer would play an important role in the propagation reactions of 3-(4-butylphenyl)thiophene. This originates from the highest spin density at the 5'-position of the HT dimer and the low probability of the HH coupling due to the steric hindrance between thiophene ring and phenyl group.
机译：为了获得一步法形成区域规则的α-共轭的低聚和聚噻吩的理论基础，使用密度泛函理论（DFT）通过分子轨道计算阐明了3-取代的噻吩和低聚（3-甲基硫烷基噻吩）s的电子态。具有Becke型的三个参数功能（B3LYP）和6-31G（d）基本集。从计算出的各个自由基阳离子的未成对电子自旋密度推断出单-和低聚噻吩的偶联反应的反应性，并估计了与在氧化过程中产生自由基阳离子的能量相对应的电离电势。根据自旋密度的大小，可以很好地理解3-（甲基硫烷基）噻吩低聚的主要区域选择性产物（J.Org.Chem.61（1996）8285）。由于甲基硫烷基侧链之间的位阻不会干扰噻吩环的2位（C-2）之间发生的偶联反应，因此3-（甲基硫烷基）噻吩的引发反应是头对头的产生（HH）二聚体。另一方面，头尾（HT）二聚体在3-（4-丁基苯基）噻吩的扩散反应中起重要作用。这是由于在HT二聚体的5'-位具有最高的自旋密度，以及由于噻吩环和苯基之间的空间位阻而导致HH偶合的可能性低。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号